Going back about 64 years I was an apprentice and I had to produce some aluminium sealing washers for the aircraft industry.
Producing them and parting them off was not a problem but holding them to finish the parted face was. The foreman then explained how he had done a few years before.
An aluminium bar was held firmly in the chuck and a recess which located the washer but was not a tight fit was machined in the face. The recess was then filled with grease and the washer then bedded into it, with an extremely sharp tool and running at 1000 rpm it was possible to face it to size with very light cuts.
Producing them and parting them off was not a problem but holding them to finish the parted face was. The foreman then explained how he had done a few years before.
An aluminium bar was held firmly in the chuck and a recess which located the washer but was not a tight fit was machined in the face. The recess was then filled with grease and the washer then bedded into it, with an extremely sharp tool and running at 1000 rpm it was possible to face it to size with very light cuts.